Immunity to wild type Toxoplasma gondii may be induced in cats by bradyzoites of an oocyst negative strain, T-263. A feline vaccine based on this premise would serve to reduce toxoplasmosis in humans by reducing environmental oocyst contamination. Successful commercialization of a vaccine depends on production of tissue cysts and bradyzoites in cell culture, the objective of Phase I.The bench scale method for tissue cyst production developed in Phase I will be scaled up for maximum production during Phase II. The process will be adapted to microcarrier cell culture and scaled up to batch production at the 5 liter bioreactor scale.